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cannot diagnose fuel problem

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Posted by: APOLLO24

2000 v8 92k miles. ok here's the deal. car was running fine. shut it off to run to the store. came back turned her on and had rough idle. felt like rpm's were at 2500 but it was at 7000. exhaust did not seem clogged (like cats) cause when i gave gas she was fine. at the red lights again the same rough idle situation. brought her home and parked. 5 hours later turned her on with a real rough start. it started to run for a 5 seconds and when i lightly tapped gas in park and it went dead. THAT'S IT. now i turn the key and it sounds like it's out of gas. i have full gas tank. changed fuel filter first. nothing. any problems with fuel pump relays that i should know about or fuel pumps in general? i think that's the problem. can someone help diagnose. oh by the way, the next day i turned it on an it started for half a second and that's it. crank crank crank. as always thanks in advance guys.

Posted by: wm_sorg

Do you hear the fuel pump prime when you turn the key to the on position? If not you can do a relay swap to see if the problem is the FP relay. The FP relay is block 15 in the fuse box under the hood. You can borrow one of the others and try again. Also you can check to see if there is pressure in the fuel rail by tryig to bleed the shrader valve. Good luck.

Posted by: Redwingvksm

Does sound like a fuel pump. Have someone get into the car, you get under the gas tank (or atleast as close as you can) and than have the other person just turn ON the vehicle. If you don't hear a buzz/whine your Fuel Pump is gone.

Posted by: APOLLO24

i'm gonna go through that thanks. are the fuel pumps notorious to go bad on this car? i had it since brand new. is it easy for me to replace fuel pump? i replaced valve cover gaskets on my own to give you idea on my skill. thanks fellas.

Posted by: APOLLO24

one more thing. if it was the just the relay wouldn't i not be able to have started that one time at all instead of that rough idle? it was just weird that it went like that instead of just not starting at all. thanks

Posted by: Quik LS

sorry to ask - V8 or V6?

it could also be a vacuum leak - which shows more at idle.

and no - fuel pumps have not been a common issue.

Posted by: LincolnTech38

instead of guessing get a fuel pressure guage and check fuel pressure.

Posted by: 2001LS8Sport

Quote:

Originally Posted by LincolnTech38

instead of guessing get a fuel pressure guage and check fuel pressure.

+100000000000000

Posted by: APOLLO24

switched relay #15. no luck. put my ear to the gas tank and heard a very slight whine when the key was turned. did it once. all the other times i tried it it did not whine so i have no clue if the fuel pump works or not. i have the CEL on but have no way of getting it to autozone for the check. any ideas appreciated . thanks

Posted by: beaups

Buy a code scanner or have it towed to a mechanic??? As for CEL you may not have a code. I believe CEL stays on when engine is not running.

Posted by: APOLLO24

i was trying to avoid the cost of towing and the experience of a clueless mechanic. this board has always helped me solve problems. i got the check engine light when the car was running. before i shut it off. later when i tried to start it was when it didn't start. i had CODE P0153 slow response bank 2 sensor 1 CKT come up a few times in the past year and i never fixed it.

Posted by: beaups

gotcha. Dealer would be a safe bet though. Seeing you need a new 02 sensor anyhow why don't you start there?

Posted by: APOLLO24

the dealerships in the ny tristate area are the worst. i could list pages of the issues that i had with them. i branched all the way out to nj at hillside auto. my car was overheating and no one could fix it. with the help of the guys here i saved thousands when they isolated the hydro fan pump only. not thermostats, not hoses. not entire fan assemblies. this site has been great. i just can't figure out why car won't turn over. normally this car is notorious and the problem is spread out with it's owners that's why i'm relying again on LVC to help me out. would the 02 sensor cause the car to not start by screwing up the cat? just don't want to change fuel pump either if quik says its not notorious b/c i think i heard it also.

Posted by: Quik LS

IB the O2 sensors are only used in 'closed loop' conditions - where the car is using the O2 sensors to adjust fuel/air mix. THe car will not go into 'closed loop' for a couple of minutes after startup - so a bad O2 shouldn't be the cause.

Posted by: Redwingvksm

Quote:

Originally Posted by LincolnTech38

instead of guessing get a fuel pressure guage and check fuel pressure.

Also, just because you hear a whine doesn't mean you'll have fuel pressure.